JSCS - Vol 73, No 6

JSCS Vol 73, No. 6

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J. Serb. Chem. Soc. 73 (6) 597–607 (2008)
UDC *Sempervivum marmoreum L.+66.061:615.28; JSCS–3742; doi: 10.2298/JSC0806597S; Original scientific paper

Comparative screening of the anti-oxidant and antimicrobial activities of Sempervivum marmoreum L. extracts obtained by various extraction techniques
SASA S. STOJICEVIC, IVANA T. STANISAVLJEVIC, DRAGAN T. VELICKOVIC*, VLADA B. VELJKOVIC and MIODRAG L. LAZIC

Faculty of Technology, Bulevar oslobodjenja 124, Serbia

*Zdravlje-Actavis, Vlajkova 199, 16000 Leskovac, Serbia

(Received 10 September, revised 31 December 2007)

This paper presents a comparative study of the anti-oxidant and anti-microbial activities, total phenolic compounds and total flavonoids in extracts obtained from houseleek (Sempervivum marmoreum L.) leaves by the classical (maceration), ultrasonic and Soxhlet extraction (CE, UE and SE, respectively). The extract obtained by the CE contained higher AMounts of phenolic and flavonoid compounds and showed a better antioxidant activity than those obtained using other two techniques. All the extracts, independent of the extraction technique applied, showed antimicrobial activities against Aspergillus niger and Candida albicans only but not against the tested bacteria.

Keywords: antimicrobial activity; anti-oxidant activity; extraction; houseleek; Sempervivum marmoreum L.; ultrasound.

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J. Serb. Chem. Soc. 73 (6) 609–618 (2008)
UDC 599.735.5+591.436+66–946.1:591.478–035.57; JSCS–3743; doi: 10.2298/JSC0806609A; Original scientific paper

Immobilization and characterization of bovine liver catalase on eggshell
ÖZLEM ALPTEKİN, S. SEYHAN TÜKEL and DENİZ YILDIRIM
University of Çukurova, Faculty of Sciences and Letters, Department of Chemistry, Adana 01330, Turkey

(Received 12 September, revised 21 December 2007)

Bovine liver catalase immobilized on eggshell particles was characterized and the reusability of the immobilized catalase was investigated in a batch type reactor. For immobilized catalase onto ground eggshell (ICATG), the optimum initial AMount of catalase was 85 mg g^-1 of eggshells, the optimum pH was 6.0 (75 mM citrate buffer) and the temperature was 30 °C. The V_max and K_m values of ICATG were determined as 29.1±1.2 U/mg of protein and 41.9±2.7 mM, respectively. The reusability of ICATG was tested and the remaining activity of ICATG was found to be 73 % of the initial activity after 80 cycles of batch operation. The AMount of catalase bound onto the carrier was estimated by using the results of induced coupled plasma measurements. The catalytic efficiencies (k_cat/K_m) of free catalase and ICATG were found to be 1.4´10⁶ and 2.8´10³ dm³ s^-1 mol^-1, respectively. Catalase immobilization onto eggshell is economic and has good reusability. Hence, it can be concluded that eggshell is an efficient carrier for immobilizing catalase.

Keywords: catalase; eggshell; immobilization; glutaraldehyde; induced coupled plasma.

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J. Serb. Chem. Soc. 73 (6) 619–630 (2008)
UDC 546.962+542.913:576+615.9; JSCS–3744; doi: 10.2298/JSC0806619G; Original scientific paper

Synthesis, structural characterization and cytotoxic activity of two new organoruthenium(II) complexes
SANJA GRGURIC-SIPKA, MOHAMED AL ARBI M. ALSHTEWI, DEJAN JEREMIC, GORAN N. KALUDJEROVIC*, SANTIAGO GÓMEZ-RUIZ**, ZELJKO ZIZAK***, ZORICA JURANIC*** and TIBOR J. SABO

Faculty of Chemistry, University of Belgrade, Studentski trg 12–16, 11000 Belgrade, Serbia

*Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, Njegoseva 12, 11000 Belgrade, Serbia

**DepartAMento de Química Inorgánica y Analítica, E. S. C. E. T., Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain

***Institute of Oncology and Radiology, 11000 Belgrade, Serbia

(Received 27 December 2007, revised 4 March 2008)

Two new p-cymene ruthenium(II) complexes containing as additional ligands N-methylpiperazine ([(η⁶-p-cymene)RuCl₂(CH₃NH(CH₂)₄NH)]PF₆, complex 1) or vitAMin K₃-thiosemicarbazone ([(η⁶-p-cymene)RuCl₂(K3tsc)], complex 2) were synthesized starting from [(η⁶-p-cymene)₂RuCl₂]₂ and the corresponding ligand. The complexes were characterized by elemental analysis, IR, electronic absorption and NMR spectroscopy. The X-ray crystal structure determination of complex 1 revealed “piano-stool” geometry. The differences in the cytotoxic activity of the two complexes are discussed in terms of the ligand present.

Keywords: ruthenium(II) complexes; p-cymene; K₃-thiosemicarbazone; N-methylpiperazine; cytotoxic activity.

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J. Serb. Chem. Soc. 73 (6) 631–639 (2008)
UDC 544.526.5+542.92+547.56:546.3–386+546.215; JSCS–3745; doi: 10.2298/JSC0806631L; Original scientific paper

Photocatalytic degradation of Phenol Red using complexes of some transition metals and hydrogen peroxide
SAVITRI LODHA, DIPTI VAYA, RAKSHIT AMETA and PINKI B. PUNJABI
Photochemistry and Solar Energy Laboratory, Department of Chemistry, University College of Science, M. L. Sukhadia University, Udaipur – 313002, Rajasthan, India

(Received 27 July, revised 20 December 2007)

The photocatalytic degradation of Phenol Red was investigated using thiocyanate complexes of iron, copper, cobalt and hydrogen peroxide. The rate of photocatalytic degradation of the dye was followed spectrophotometrically. The effect of the variation of different parAMeters, such as pH, concentration of the complexes and dye, AMount of H₂O₂ and light intensity on the rate of photocatalytic degradation was also studied. A tentative mechanism for the photocatalytic degradation of Phenol Red is proposed.

Keywords: photocatalytic degradation; Phenol Red; metal complexes; hydrogen peroxide.

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J. Serb. Chem. Soc. 73 (6) 641–654 (2008)

UDC 544.032.4:66.094.1:546.92+544.478+546.26; JSCS–3746; doi: 10.2298/JSC0806641E; Original scientific paper

Temperature dependence of the kinetics of oxygen reduction on carbon-supported Pt nanoparticles

NEVENKA R. ELEZOVIC, BILJANA M. BABIC*, NEDELJKO V. KRSTAJIC**, SNEZANA LJ. GOJKOVIC** and LJILJANA M. VRACAR**

Institute for Multidisciplinary Research, P. O. Box 33, Belgrade, Serbia

*Vinca Institute of Nuclear Sciences, P. O. Box 522, 11001 Belgrade Serbia

**Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia

(Received 11 July, revised 20 November 2007)

The temperature dependence of oxygen reduction reaction (ORR) was studied on highly dispersed Pt nanoparticles supported on a carbon cryogel. The specific surface area of the support was 517 m² g^-1, the Pt particles diAMeter was about 2.7 nm and the loading of the catalyst was 20 wt. %. The kinetics of the ORR at the Pt/C electrode was exAMined in 0.50 mol dm^-3 HClO₄ solution in the temperature range from 274 to 318 K. At all temperatures, two distinct E–log j regions were observed; at low current densities with a slope of –2.3RT/F and at high current densities with a slope of –2.3´2RT/F. In order to confirm the mechanism of oxygen reduction previously suggested at a polycrystalline Pt and a Pt/Ebonex nanostructured electrode, the apparent enthalpies of activation at selected potentials vs. the reversible hydrogen electrode were calculated in both current density regions. Although ∆H_a,1^≠ > ∆H_a,h^≠, it was found that the enthalpies of activation at the zero Galvani potential difference were the sAMe and hence it could be concluded that the rate-determining step of the ORR was the sAMe in both current density regions. The synthesized Pt/C catalyst showed a small enhancement in the catalytic activity for ORR in comparison to the polycrystalline Pt, but no change in the mechanism of the reaction.

Keywords: oxygen reduction reaction; platinum catalyst; carbon support; temperature dependence; enthalpy of activation.

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J. Serb. Chem. Soc. 73 (6) 655–659 (2008)

UDC 543.551/.552+547–36:546.11'98+541.135.5; JSCS–3747; doi: 10.2298/JSC0806655J; Short communication

Short communication

Coulometric–potentiometric determination of pKA of several organic bases in propylene carbonate

LJILJANA N. JAKSIC and RADMILA M. DZUDOVIC*

Faculty of Mining and Geology, University of Belgrade, Djusina 7, 11000 Belgrade Serbia

*Faculty of Sciences, University of Kragujevac, Radoja Domanovica 12, 34000 Kragujevac, Serbia

(Received 30 November 2007, revised 4 February 2008)

The pK_A values of protonated triethylAMine, pyridine and 2,2'-dipyridyl in propylene carbonate (PC) were determined by applying the coulometric––potentiometric method and a hydrogen/palladium generator anode (H₂/Pd). The investigated and reference base were titrated to 50 % with protons electrogenerated from hydrogen-saturated palladium, in the presence of sodium perchlorate as the supporting electrolyte. The half-neutralization potentials E_1/2(x) and E_1/2(st.) of the investigated and standard base, respectively, were measured using a glass–SCE pair. The obtained pK_A values were compared with those reported in the literature.

Keywords: coulometry; pKA of base; propylene carbonate; hydrogen/palladium electrode.

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J. Serb. Chem. Soc. 73 (6) 661–664 (2008)

UDC 62–405.8.004.12:544.6–188; JSCS–3748; doi: 10.2298/JSC0806661P; Original scientific paper

Supercapacitive characteristics of electrochemically active porous materials

VLADIMIR V. PANIC

Institute of Chemistry, Technology and Metallurgy, Center for Electrochemistry, Njegoševa 12, 11000 Belgrade, Serbia

(Received 27 March 2008)

The results of an investigation of the capacitive characteristics of sol–gel-processed titanium- and carbon-supported electrochemically active noble metal oxides, as representatives of porous electrode materials, are presented in the lecture. The capacitive properties of these materials were correlated to their composition, the preparation conditions of the oxides and coatings, the properties of the carbon support and to the composition of the electrolyte. The results of the electrochemical test methods, cyclic voltAMmetry and electrochemical impedance spectroscopy, were employed to resolve the possible physical structures of the mentioned porous materials, which are governed by the controlled conditions of the preparation of the oxide by the sol–gel process.

Keywords: porous electrodes; sol–gel procedure; oxide sols; supercapacitors; dimensionally stable electrodes.

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J. Serb. Chem. Soc. 73 (6) 665–671 (2008)

UDC 615.33:543.544.5:543–76; JSCS–3749; doi: 10.2298/JSC0806665M; Original scientific paper

A rapid and reliable determination of doxycycline hyclate by HPLC with UV detection in pharmaceutical sAMples

SNEZANA S. MITIC, GORDANA Z. MILETIC, DANIJELA A. KOSTIC, DANIELA C. NASKOVIC-DJOKIC*, BILJANA B. ARSIC and IVANA D. RASIC

Department of Chemistry, Faculty of Natural Sciences and Mathematics, Visegradska 33, 18000 Nis, Serbia

*D. D. ”Zdravlje–Actavis” – Pharmaceutical and Chemical Company, 16000 Leskovac, Serbia

(Received 14 September, revised 7 November 2007)

An accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantification of doxycycline hyclate in pharmaceutical sAMples has been developed and validated. The drug and the standard were eluted from a Lichrosorb RP-8 (250 mm´4.6 mm, 10 mm particle size) at 20 °C with a mobile phase consisting of methanol, acetonitrile and 0.010 M aqueous solution of oxalic acid (2:3:5, v/v/v). The flow rate was 1.25 ml min^-1. A UV detector set at 350 nm was used to monitor the effluent. Each analysis required no longer than 4 min. The limits of detection and quantification were 1.15 and 3.84 μg ml^-1, respectively. Recoveries for different concentrations ranged from 99.58 to 101.93 %.

Keywords: high performance liquid chromatography; doxycycline hyclate; ultraviolet detection.

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J. Serb. Chem. Soc. 73 (6) 673–680 (2008)

UDC 553.492.004.54:504.53:58.051; JSCS–3750, doi: 10.2298/JSC0806673M; Original scientific paper

Methods for the determination of the form of aluminium: Pseudogley soils

VESNA MRVIC, MIODRAG JAKOVLJEVIC*, DRAGI STEVANOVIC*, DRAGAN CAKMAK and MIRJANA ZDRAVKOVIC

Institute of Soil Science, Teodora Drajzera 7, Belgrade, Serbia

*Faculty of Agriculture, Nemanjina 6, Zemun, Serbia

(Received 26 November 2007, revised 18 March 2008)

Exchangeable aluminium (Al_KCl) and CaCl₂-extractable aluminium (Al_CaCl₂) have approximately the sAMe value in the prognosis of detrimental effect on plants. Additional, more in-depth research should show which of the two applied methods of exchangeable Al determination is more suitable (after Sokolov or using aluminon). The contents of total Al and AMorphous Al increase with depth and percentage clay. Crystalline Al oxides and CuCl₂-extractable aluminium (Al_CaCl₂) and EDTA-extractable aluminium (Al_EDTA) represent the more mobile reserves of Al and they depend mostly on changes in the acidity parAMeters of the soil. Exchangeable Al is on average 4.3–4.7 times lower than the contents of Al_CaCl₂ and Al_EDTA, 8 times lower than crystalline Al and 35 times lower than AMorphous Al. Some methods are not sufficiently selective, hence further research is required to achieve more favourable methods for the determination of the different forms of Al.

Keywords: exchangeable Al; Al oxalate; Al dithionate; CuCl₂ extractable Al; organic Al.

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J. Serb. Chem. Soc. 73 (6) 681 (2008)

Errata

Errata

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